goods returned

I bought a remote controlled car last week. On giving the gift to my grandson we found it did not work. I returned to the store today and requested my money back. It was pointed out to me that on leaving the store the cash slip had been stamped with a stamp saying 'NO GUARANTEE' as I had not allowed them to test it before leaving the store. I was unaware that this was what was stamped on the invoice as many stores check invoices as you leave tstore to ensure that the goods are paid for. After much threatening with the Consumer Council etc. I got my money back. I want to warn people against this and also bring to the attention of the Consumer Council that at the top of the invoice they state that no cash refunds will be made. Is this not *******?