Non-Existent Service! They will not return my money!!!

I handed in my apple watch to replace the battery in around December at the V&A Waterfront. When I went to collect my watch, they said it had not left and had not been fixed. This was after around a week of them having the watch and when I went to hand it in they said it should take around 7 days. So once they said it had not been fixed, they said they would refund, and 12 weeks later, no refund (R350 as the deposit fee) has been given. I have been chasing this company since, and have not been given any successful information as to help. I have also messaged them on Whatsapp, and it only has one tick. This company is a disgrace!