Zando doesn't make good on their refund promise

Two months of very frustrating poor service to obtain a refund. They delivered to my mother early around 6th December - the gift i bought her didn't fit. We immediately notified them and requested a refund. The item was collected the next day. I waited patiently the whole of December for my refund - nothing came. Followed up the beginning of January 2020 - they claimed it wasn't collect. We provided them with the name of the person, and courier service that collected. After fighting about this for almost 3 weeks they conceded that it was indeed collected and that the refund was agreed upon and a voucher loaded on my Zando account. The Voucher they gave doesn't work and there is no credit on my account. I have sent them 3 emails already with no joy or response. My advise: don't buy from them