Universal Transaction Processing Limited Nightmare OC2 & OC3

Hi, does anyone have any experiance or dealing with using UTP (Universal Transaction Processing Limited) with opencart?
http://www.universaltp.com/

A friend signed up to them but I have nothing but problems with trying to integrate their payment module on OC2.3.0.1 and 3.0.2.0
Here is a summary of what I have emailed their support dept, but support requests are either ignored or badly answered. The latest from the UPT rep is that it is the website owners responsibility to sort the connectivity out between the OC site and the gateway. Even though they proved the module, it doesn't work .. or I cannot get it to work.
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Margret. Here is a summary of the issues I have faced. (Part of this message RE the technical side has been emailed to support hours ago, which is a disgrace. 3+ hours response time, and responding with the same repeated unhelpful replies)

I have tested both relevant file-sets emailed to me by UTP support with stock (unmodified) installations of
Opencart 2.3.0.1
Opencart 3.0.2.0

with the test account data UTP provide

Both fail.

On opencart 2.3.0.1.. I am able to get the gateway installed without error and connect. However the system throws back the following errors.

Onsite payment errors are either
1) a failure to send the Password Response Value in 3D secure mode
2) All test transactions (successful or failed) with test data causes a 'page not found' error within the iframe, not the expected 'failed/success transaction notice'. Looping the website within itself. (Screen-grabs Attached)

Offsite/Redirected payment errors are
1) The UTP payment page timing out (about 30% of the time).
2) Not returning the website visitor from the UTP payment page (https://gateway.universaltp.com/paymentform/) to the originating website for the 'failed/successful transaction notice'.
3) Or your offsite payment page returns
ERROR: 66343 - ERROR CODE (RC_INVALID_SIGNATURE)

either way, the files sent by UTP for OC 2.3.0.1 do not work as expected and redirected payment pages are showing to be unreliable. And all of this is just in test mode!

The problem is worsened on OC 3.0.2.0. Where the module will either not install throwing back a generic server error. Or it does install successfully, but when I go to modify the module settings (extension/payments/utp) via the OC backoffice, it causes a WSoD.

So far, the files sent and your systems are not fit for purpose. Furthermore, your own backlinks in the code throws back an invalid SSL cert. This does not fill me with confidence.
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I have attached their payment module if anyone is interested, come with instructions on setting up a test account once installed on OC.

The problem is worsened on OC 3.0.2.0. Where the module will either not install throwing back a generic server error. Or it does install successfully, but when I go to modify the module settings (extension/payments/utp) via the OC backoffice, it causes a WSoD.

What is the generic server error message provided during the event?

Hi Straightlight,
"Internal Server Error" when installing or uninstalling on OC3.
Nothing is recorded in Cpanel error logs or the OC Error list.

My mates site is based on 2.3.0.1, was hoping to just get the payment gateway working, Ideally on OC2.3, but no big deal to upgrade him to OC3 if it meant getting this payment gateway to work.

Sadly this UTP company are not bothered. Support is awful, when they reply!
Massive cancellation fee from UTP! So my mates stuck with them.

any help or advice you can give on this is greatly appreciated!

Nothing is recorded in Cpanel error logs or the OC Error list.

An internal server error message would indeed display in your cPanel error logs would be enabled. See from your FTP root logs path the most recent error line you can find regarding the error index 500.

Hi, nope, there be no 500 errors in the cpanel logs. Not a sausage.

I (think I ) have narrowed the problem down to UTP's callback, causing a 'page not found' within opencart 2.3.0.1 on a failed or successful test transaction. No idea how to fix it yet.