Does a landlord need to replace a dirty matress in a furnished home?

Hi, my friend and I just moved into a furnished place which we inspected however when we moved in today and lifted the sheet off of one of the beds, we found a filthy mattress and need to know if we are eligible for it to be replaced as it is included in the inventory and condition report. It really frustrated us but understand if we need to cop it but want to see if there is anyway we can get it sorted.