Gas oven cutting out

Hello all! We’re a bit worried about our Hotpoint gas double oven. Model: HDM67G0C2CX
We bought it in February this year.
We used it about once or twice a month. A few times, the top oven would cut out between about 2-10 minutes of it being lit. It would blow out the smell of gas, then cold air. When re-lit, it would sometimes do this again or sometimes be ok.
We read instructions to make sure we were lighting it properly – we were.
It said sometimes the new smell has to burn off, so we convinced ourselves this problem would resolve.
It hasnt, so we called the shop and they sent a Hotpoint engineer.
The engineer found it had a lose earth on the thermocouple. He tightened it.
He also said this model sometimes had excess insulation, which causes flame to lift off the burner and cut out. So he pushed the insulation somehow, at the top, to help the problem.
We have the letter from the engineer, saying what he did.
The top oven worked the first time we tried it next day. It cut out the next time, with the same smell of gas, then cold air.
So a different Hotpoint engineer came again, a few days ago.
He also said this model has excess insulation and lacks airflow, causing the flame to lift off the burner.
His solution was to tilt the oven backwards, to access the underside of it.
He undid some screws that hold the bottom plate of the oven on. He put spacers in, then tightened the screws.
He said this would allow more airflow and cure the problem.
We’ve used the top oven once and it didn’t cut out.
But since loosening the base, the door of the bottom oven doesn’t close properly. It’s lose. We can open and close it with one finger.
We’re also wondering if losening the oven base means the oven is less insulated and will use more gas?
Like if you’re trying to heat a room but leave the window open a bit.
We bought an extra 5 year warranty from the shop when we bought the oven. They’re sending another engineer.
Do you have any advice please?