Praise be to Allah.Al-hamdu lillaah.
Yes, this extra amount is undoubtedly considered ribaa, as the longer period for payment they allow you the more they increase the amount for you to pay. You need to refuse this kind of transaction. If you are forced, then pay the original sum without the extra amount. If you are forced to pay the extra amount, then pay it while offering repentance to Allaah and committing not to deal in such transactions again.