Glasfit- Dishonest Service

Glasfit Malmesbury sold us the incorrect windscreen. We provided the correct Chassis number etc and was assured the windscreen would fit. When we tried to fit it, it obviously did not. We called them and explained the situation and they said we were welcome to return it and receive a refund. Upon arriving at the shop, a few hours later the same day, the windscreen was all of a sudden not accepted. Glasfit stated that since we tried to fit the windscreen, they could now not take it back. The Head Office has time and again promised that we would be refunded but its not nearly two months later and there is still no refund. We are now out of pocket for a considerable amount and still don't have the correct windscreen. This is blatant thievery. How can a company sell you a product that they assure is the correct one and then refuse to give you a refund once you return the product in working order ? The excuse that every branch functions according to its own rules ( and laws it would seem) is weak and unacceptable. Various phone calls and emails have resulted in absolutely no resolution and just promises. Incredible disappointing and dishonest.