This coming from someone who shells out £250 a month
I sincerely hope you get value for money for £3000 a year!
I have been 100% happy with the Zen package, and BT Business FTTP package I had before, neither of those were even over £1000 a year, but guess if you live in the sticks it's the price you pay (I used to live in the back of beyond, BT offered me leased line (128Kbps) for a mere £12,500 per year, and that was 1990's.) I did then go with Demon ISDN, and a satellite download package, but even that was way cheaper than £2000 a year all in, and I got effectively 128K up, and 2Mbps down).
Zen are taking the obvious issue seriously now, and things are being done. I am sure it will be back to normal in a few days, meantime, they have waived charges, but I can still get 200Mbps down and 70Mbps up.
There are many ways of doing things, and I see you are happy with your way, as I am with mine. I did indeed have an SLA with BT business, but it wasn't worth a dime when the fibre was broken by a digger, save for the 4G dongle they gave me.