Faulty oven after 11 months, what are my rights?

[MrsJourns]

I bought an oven 11 months ago online from Sainsburys. On Thursday morning the oven stopped heating up ( fan and grill still working), I telephoned Sainsburys straight away.
They have arranged for a Hotpoint engineer to come on Tuesday. They will either fix the oven or if it is irreparable write a report for Sainsburys stating this.
My big panic is if they cannot fix it, I will be ovenless for Christmas. The earliest Sainsburys will get the report and ok a refund is Wednesday (they no longer sell ovens), and then it will take 3-5 working days for us to receive the refund. Even if I purchase an oven on the Tuesday, it is going to be very difficult to get delivery and fitted by Friday.
To make matters worse one of my children has coeliac disease and food allergies meaning I make/ bake all of his food. It is very difficult ( and expensive) to find prepared food he can eat.
I have explained all of this to Sainsburys, all they have done is put me on hotpoints waiting list for a cancellation appointment.
What are my rights with Sainsburys?
Does anyone have any advice on how I can guarantee
a working oven for Christmas?

[Lonecatwithkitten]

John Lewis have a range of ovens that are available for next day delivery. This could be very useful to you.