Diabolical service - not even a manager can phone to apologise - 22 days later!!

I am disgusted at the lack of response and service from Zando. I placed an order for 2 sets of boots on the 04/05/2020. My app confirmed I should receive them by the 11/05/2020. On the 12th May I had still not received them so sent an email following up on my late delivery. I received a response apologising for the “huge delays” and that I will get them shortly. On the 15th May I sent another email mentioning that I had realised that the 1 pair of boots had received a discount since I’d placed my order and I asked if they would consider giving me the discount considering that I had not as yet received my boots. Zando rep**** back confirming that “since it was neither Zando’s nor my fault” I would not be getting the discounted rate, but I was more than welcome to cancel that order and reorder the boots again. What the consultant failed to notice was that my size was no longer available on the discounted option. I then rep**** back immediately and asked if they could please give me an estimate on when I can expect to receive my order. They only rep**** back on the 18/05/2020 stated that my order had been with the couriers since 7th May (!!!) and that I could expect it during the course of the week, and would receive a call prior to delivery. By the 29th May I had still not received my order and sent a written complaint asking for a manager to contact me. I finally received my order 1st June. I sent Zando an email confirming that I'd received the order but I still expected a call from the manager. It is now the 22nd June and I have as yet still not received a call or even a written apology for the diabolical service. This is how they treat clients who have been dealing with them for 5 years. I will be cancelling my app and will never ever order from Zando again.