Brilliant piece of TV (55", 4K, 8-bit HDR, Freeview Play, Amazon Video/Netflix, etc.) at an incredible price imo. Haven't seen it lower than £450 before but there's a way you can get it for £413.05.
1) Call AO Price Match 0344 324 9222
2) Ask them to price match the H55M3300 on Argos WITH the TV10 10% discount code - Argos price should come out to £453.05 with delivery
3) Ask for AO Big Weekend discount on top, AOBIG40, for further £40 off bringing total to £413.05 delivered
I did this last Sunday when the £50 off AO promotion was running and I got the same TV for £403.05. I don't see why it wouldn't work again with the £40 off discount.
Just a few things to note. It took me two tries to get this deal to work. First time I asked the rep for the price match and THEN asked for the further £50 off to which he said you can't have both. Second time I asked the rep first whether I can have both discounts stacked and after she said yes I proceeded with the steps above. Truth be told I think I just got lucky with who I spoke to. ToC says you can't say stack discount on top of Price Match. If first rep doesn't give the deal just hang up and try again after a while.
Second, be a bit patient. AO took a while finding the TV on the Argos site and needed my help adding the TV10 promo code so be prepared to help them out.
Hopefully this helps someone! Any questions just ask.