Still waiting for my new phone battery

Apple admits to slowing down batteries for older iPhones... Book your phone in online they said (on Fin24) for a discounted rate for the replacement battery.

Appointment booked on the 27th January 2018, 10h00 at the Cavendish iStore.

Take the phone in and they say great will have it ready in 7 days (not 7 working days)... 7 days comes and goes - you think oh maybe they meant 7 working days so you wait. Then they say that they do not have stock of the replacement part.... Sorry what??? You discount the price of the repairs and now you have no stock??? Honestly how does that work??

It is now the 15th February. Last communication was on the 12th February 2018 stating "that your unit has moved into a In Progress Status. Time for this status may vary due to weekends dependent on the repair volumes being experienced." YOU DON'T SAY... 7 days to 20 days and counting....

"Average turn around time is two to three working days. We will however keep you updated when the status changes."

Honestly how long does one have to wait???