'No Sir, I will not let you spend £4000 in my Ernest Jones' UPDATED

[Umbongo]

I'll wait to see what they say tomorrow, with the intention of letting them know that if they would like my business then an additional PO rubber strap to compensate for the inconvenience will ensure I buy from them.
Otherwise, having browsed the online offers, my business will be going elsewhere and I'll forgo the convenience of the 0%.

Spoke to my wife regarding the way forward on this (several years in both big name and independent jewellery management and more still in retail in general).
Her advice was very concise - "don't go in there saying "I want this and that to compensate me" - go in there and say "what can you do for me?" and just calmly wait for their answer."
Id say keep saying "no" until youre happy with their offer, or walk away. If theyre any good they'll ask what you want to make the sale happen, if not, hint gently and, if theyre not biting, go somewhere that does bite - though if you manage to establish youre entitled to interest free AND 10% you've won anyway!