Unwillingness to help customers - passing the buck to loyalty partner

My husband and I have been trying for the past 3 weeks to switch our Smartshopper points to Avios as there was a promotion running until the end of October to get bonus Avios - which has since lapsed leaving us stranded.

We had a similar problem in 2015 to do the same. At that time, a lady from PicknPay did more than her best and resolved the matter by getting Avios on the phone and made it happen. Now both Avios and PicknPay's call centres say that the accounts are linked according to them, but we can't switch any points online or at the kiosks as a message 'call the call centre - account is not linked' is displayed. Nobody wants to help or try to correct this so we're stuck. Is service too much to ask? Numerous telephone calls were made from our side to try and resolve this.