Check your purchase contract and plans of the apartment first of all. If these show/state a set of patio doors – then the developer must provide them or pay you compensation.
If they are not specified in your contract/plans then it is more difficult. Many developers state in their contracts and marketing literature that they reserve the right to alter the specification of the property without consultation.
So check your legal paperwork first – then talk to the developer or your agent. Be prepared for a “fight” if your contract/plans do not specify the patio doors as a feature and you want to have them. There are quite a few threads on this site which deal with developers who change specs. to properties. It might mean a wade back a few months – but it is well worth trying to find them!