Having followed all this raised a call with our fibre supplier as well to check (we had done all the elementary checks with our router and everything in house) but noticed another app we couldn't get into.

Turns out they were aware of an issue which they have now resolved. 
I have finally been able to get in.

One lesson learnt out of this for Intuit?

Would it be possible to pre warn us when updates are being pushed and the usual requirements we have to do to make sure there are no issues our end?