Opencart 2.0 shipping method with select option

Hello,
I wrote my own shipping method using local shipping company`s API,It`s dynamic and you can choose your city and than get all the offices in it.So I have two selects
I`m using AJAX Quickcheckout.
I made it using pure html code (select) for a shipping title

Like this..kinda
$quote_data['custom_shipping'] = array(
'code' => 'custom_shipping.custom_shipping',
'title' => '<select><option></option></select>/<select><option></option></select>',
'cost' => 0.00,
'tax_class_id' => 0,
'text' => $this->currency->format(0.00)
);
I than save to the session his option for office using javascript.

However I encountered quite a few issues later on,so I was wondering if there was a batter way to do it.
I thought about creating different $quote_data[] for every office there is,but I want to have two selects.
Is there a better way of doing this?