Extended warranty???? ****

I bought A JBL SB350 from Dion Wired, as per usual they convinced me to take the extended warranty, and I did. Its an awesome unit and was very happy with it until it started to cut and completely switch off after say 30 to 45 minutes or if the volume has gone higher than 60%. I sent it to Dion Wired in Menlyn in June 2019, over a month later of having to call them all the time I got the unit back but it still had the same problem. I sent it back to them on the 3rd of August, from the 3rd of August till today I haven't received any help. As a matter of fact when I called them they told me the unit was received back from Repairs and upon testing it themselves they found that the unit is still faulty. So I have been without my Sound bar for about 3 months now. Their Managers say this and that and they will call again the following day but that just never happens. I am so disappointed that such a respectable shop gives such poor service, its like I'm the crazy one here. 3 months, as a matter of fact over 4 months and I still am the one that has to call them and there is no help.