customer tired of being harassed

hi all i have recently had the worst experience with fone choice / finchoice. my debt bounced back due to my card being ****** so i made payment via eft to their account, for the past 3 weeks now ive been sending my proof of payment to them and each day i am receiving up to 4 calls aday from their collections department saying i havent paid my account. yet i also have recieved smses and emails saying my account is up to date. when i ask to speak to a manager or director the phone is put down in my ear. im at the point where i want to sue this company due to them constantly harassing me for a payment that was made on the 27th of may but up until today i am still recieving calls saying they havent recieved my payment. they are completely unprofessional and no one there knows how to do their job. i will not do business with them in the future and will also warn people about purchasing from them.