Well if the contract was not dated, I would argue the date they put the matter in the computer is the true date. If it is, you gave the landlord plenty of time (31 days). So at this point I would put your position in writing and contact the consumer protection agency in your state that handles landlord tenant matters. Further, I would if the first doesn't work, file the matter in landlord tenant or small claims court to obtain your refund plus court costs.