£3.5k to spend on Amex in 3 weeks

Solved - 3.5k added to Octopus Energy account which could be withdrawn then once voucher lands. Worst come worst ; have just pre paid the next years energy bills.

Have the cash in savings, but need to spend 3.5k on my Amex to get reward voucher in next 3 weeks.

Have a small bank loan with Sainsbury’s bank, but I can’t seem to work out a way to pay for it via Amex.

Anybody got any ideas how I can spend £3.5k in next 3 weeks, sensibly?

• edit

I think a few people have got the wrong end of the stick. I’m not looking to WASTE £3k, where could I basically pre advance pay for things that would be worthwhile doing. The companion voucher is worth it as I plan to go to Hong Kong with the voucher this year, so saves me 90k Avios points.