Be sure to check whether your off-plan builder in Bansko is not in breach of your preliminary agreement. There is a general ban for issuing planning permissions in Bansko, issued by the mayor of Bansko. The ban is set for several areas of the town, so you should check whether your apartment is not in a to-be-building, located in the mentioned areas.
If your investment is still in the planning stage, it's likely the builder doesn't have planning permission. This situation will probably affect the deadlines in your contract. If so, it is your chance to get rid of your bad investment, by terminating your agreement unilaterally on the ground that the builder will not fulfill their obligation in the terms set in the preliminary agreement. Be sure to consult an independent lawyer, in order to get a clearer picture of the situation and independent evaluation your your case.