Worst service ever from Builders warehouse

So I bought River sand on the online store of builders warehouse on Friday the 6th of July and it was delivered on Wednesday the 10th and was not used. After realising that I was made to buy the wrong sand I called the builders warehouse number that is on the site on Friday the 12th of July and I spoke to a lady named Shanè (very friendly) and told her my story and that the sand hasn't been uses yet and asked if its possible to return it and she spoke to the centurion store and she said someone from the store will call me and give me details on how I can return the sand. That was in the morning. I later called because I had not received a call from anyone from the store and a lady by the name Zonke assisted me (very nice lady) and she mentioned a guy by the name Ernest Khumalo the store manager will call me but never did. I called again on Saturday morning the 13th of July and I spoke to a lovely lady by the name of Shakira and she went all out trying to get a hold of the store I eventually after I had to call again in the afternoon I was transferred to the store and I spoke to the manager on duty at the timeon the day forgot his name and he said he needs to arrange with the supplier to get them to come and get the sand and he can only do that on Monday and he said he will call me Monday morning. Monday I waited for a call, Tuesday I waited for a call. Today Wednesday the 17th I called and I was transferred to the store and I was told that the sand is not refundable. To my surprise this whole time i was under the impression that the sand is refundable. All the long calls and waiting for someone to call. This is the worst service ever.