Beware losing your Tesco pay as you go sim [may apply to other providers...???]

My mum has lost her mobile, she is 85 and has dementia....
It could be hidden anywhere in the house, or accidently binned and in a land fill...??????
I searched but couldn't find it.

She had it for emergency calls, and was told many times to never switch it off...
Which of course she did, so I couldn't ring it to locate if it was anywhere in the house...

Man in Tesco mobile mini shop said it would be possible we could get a replacement sim so as not to lose the credit.

I phoned Tesco mobile, and a very helpful assistant said she'd help as best she could, but I'd need to pass security checks.

I explained the situation, estimated the amount of remaining credit, provided 3 numbers that would definitely have been logged calling the sim
[she could not verify that I had stated correct numbers due to data protection],
and asked for any suggestions how I could further prove ownership of the sim..

The assistant said "unfortunately you have failed security checks and cannot have a replacement, but we can block the sim to prevent fraud.."
I believe she was sincerely sorry, and genuinely understanding..

But I failed because I could not state the exact amount of credit,
dates of credit top ups, and exact amounts of credit purchases...

Info which cannot possibly be verified due to mother's dementia...!!!

All totally impossible & unreasonable hurdles which allow Tesco to keep my mum's credit [approx £40] and profit off the misfortunes of an elderly vulnerable customer...

I will pursue this further out of sheer bloody mindedness and dislike of corporate indifference and greed...