Bad after service of faulty new matress purchase online

I purchased a restonic new matress online through hifi corp On the second day after delivery I noticed 2 bumps ( lumps on top ) indicating it wasn't checked . This was near end of August I listed my complain 1 September no one bother to check in with me, Restonic SA approved my matress swop over 3 weeks ago , hifi corp keeps saying the will escalate it , then there's no stock then they say sorry ,I was told after waiting over a month it will be delivered end September, still waiting they are not calling me to update me just again saying they are on it . Till today 5 Oktober still no new matress