{Solved}Royal mail is it my best option.

Im in a bit of a delemer.

With royal mail changing there way of postage prices and weights its put me in a bit of a mess,
I sell many items with different weights but some of the way they have to be shipped is causing it to get confused.
for eg
1 x normal Bongo decals weighs 30 grams would be sent out as a letter for 60p , royal mail 0-100g letter 60p

1 x over sized bongo decal weighs 110 grams would have to be sent out in a tube Small packet £2.70 royal mail 0-750g £2.70

dont look to bad does it
but if you look
if i put 30g down for the price on the on the normal size they would still be charged £2.70 for letter,

its the small stuff that goes in letters that causing the problem,
small letters 0-100g 60p
large letters 0-100g 90p
small packet 0-750g £2.70
how would i get round this in the coding
or does anyone know of a different option.

Any please any advice would be greatful really need to get this sorted,