Bad returns experience

Good day, I ordered some Giotto School Paint in February. Because of lock down we haven't had a chance to use it at the Nursery School, but we used it at home and found out that it was a terrible product. I did my returns on the 8 bottles I received. I received an sms confirming that 8 items will be collected. When the collection company picked it up they only had 5 items on his list. I took 3 bottles out and now when I wanted to return it. I says that they took everything already. I was refunded only R258 and the total order was R526.00. Do they know what they doing??