Incorrect Motherboard Installed/Terrible Attitude

GSM Cellphone Repair Center BFN: Replaced my 32 Gig S4 Galaxy motherboard with a 16 Gig Motherboard, completely messed up my phone, Are accusing me of loading custom software. Johan***ner/Manager) of GSM Cellphone Repair Center, who won't give me his surname won't even listen to my complaints and has an extremely arrogant, unprofessional attitude and when confronted just says \they wont be threatened"as I firmly told him"