Being Charged for repair... Phone still new

I Bought my mom a phone at Ackermans in Woodmead for R999 it only worked for not even three months and the speaker stopped working... We took it back for repairs and we where told to wait three weeks then we will be contacted. But three weeks passed and I had to call to make a follow up and was still told to wait one more week which was now over a month... Yesterday I received a call From a staff member from Ackermans telling me that we have to pay R1000 to fix the speaker... I tell her it's still under warranty and she says the speaker is broken cause the phone fell in water and had liquid... So I tell her that this phone is still new and was never dropped... My mom woke up one day and the got missed calls only to find that the phone was not ringing anymore that the speaker was broken...

So can someone please do something about cause I'm not going pay R1000 for a brand new phone which the speaker just died for no reason.

The staff member was polite and provided us with good service but can this phone issue be sorted cause now my mom has no phone...