Samsung Z Flip

Purchased a Samsung Z Flip on contract. When signed up for one of the promo gifts qualified for a free screen change with an excess of R1000. After 4months of owning this brand new popular and in demand phone the screen started to bubble and was no longer able to use due to touch pad not working. Took it to Samsung Customer Care in Nandi drive who then states an additional R1300 needs to be paid in order for phone to be repaired due to screen change on the phone the back glass to will crack. This should be a Samsung problem if them changing the front screen results in the back screen being damaged. How can an almost 20k phone need a repair on top of a repair. Complete *******!