I have bought two so-called refurbished iPhones fr...

I have bought two so-called refurbished iPhones from this company. One of them took over a week to arrive because it turned out they were out of stock. They were in superficially excellent condition but had technical faults, so had to go back for repair. One came back in working order and is fine, but not the other. It is now back for a third time with another promise of a proper quality check before dispatch, or replacement. They would not honour the 30-day promise to change the model, even though I had not been able to use the phone since purchasing it. I felt this was incredibly unfair and inflexible but they wouldn't budge. I have wasted hours on the phone and going backwards and forwards to the post office.
I thought the principle of a refurbished phone was that it would work properly...
I had an iPad screen repair done and that went ok.
Overall customer experience has been disappointing and I am still waiting to hear about the on-going repair. Grrr