Pay As You Go Sim with £10 Credit - O2, Vodafone, Virgin Mobile, T-mobile (£40 for £25) ?

I have Pay As You Go Sim Cards of Virgin, t-mobile, Vodafone and O2 with £10 Credit and selling each. Each sim is £8. You can buy any with the following rates: 1 sim with £10 credit, you get £10, you pay £8 2 sims with £10 credit each, you get £20, you pay £15 3 sims with £10 credit each, you get £30, you pay £20 4 sims with £10 credit each, you get £40, you pay £25 Please contact me for details and options.