Services not rendered

I ordered and paid for a set of glasses from SpecSavers on 18 Jan 2020. Their turn-around time at the time of the first consultation is said to be "at most two weeks". I've been waiting for four weeks to get the glasses, and getting nothing but excuses for the delays. The current running excuse is that the lab has a backlog and they're working as fast as they can to clear it. Having said that, there's still no firm date on when I will get the glasses.

You always demand that all monies be paid up-front, yet don't mind not rendering the service. What type of nonsense is that? Can you cut the BS? Quickly?