Incredible Connection (The Marc) unwilling to change faulty electronics

i recently bought a volkano mega bx squared from incredible connection at The Marc in sandton , soon there after the bluetooth started to malfunction , while music plays it would just disconnect . i contacted the store to explain to them of what is happening and they asked me if i can prove i bought it at their store , i informed them that i dont have a receipt any longer but that i hav the box if that would validate my purchase, when i went into the store they insisted on the slip after having explained to them , i was then told to speak to the manager(Vusi) who already was waiting for confrontation told me that he wont change it , and that i need to go get a bank statement to prove my purchase at that store . i asked him again if he just cant change it and that i would give all my details . he said to me that no one will make him change it . i advised him that i would be complaining about the store and their unwillingness to just change a faulty music box i had bought from the store . im quite disappointed