Faulty phone that they don't want to fix

I bought a phone (Samsung J1) at woolworths in Jabulani mall on 1 August, after a few days I had a problem with the speaker. Took the phone back to the store and they told me they can't refund me because it was after 7 days but they took the phone back to Vodacom but it still had the problem, I took it back again and they did the same thing and the problem wasn't solved still. Now for the 3rd time they told me vodacom said there's nothing wrong with the phone and they can't refund me, exchange the phone or do anything with the phone (try to fix it) because they can't find any fault, even if I told them the speaker is faulty. Now my only choice is to take back this faulty phone, which I won't even use because of the speaker, I'm really disappointed at both vodacom and woolworths. Please help I just want my money back at this stage, I'm tired of this situation, I want out.