PnP Online Shopping ignores request for refund

A week ago I receieved my grocery order from PnP Online Shopping but some items were not supp**** due to no stock, but others were reflected on the invoice but short-supp****. I notified PnP Online by email requesting a refund on my credit card but received no response from TWO emails. The shortfall amount has still not been adjusted on my credit card. Not the sort of service I would have expected from a prominent retailer!