2 flat rates for shipping - next day or saturday

Hi everyone

My customer - http://www.vintagewinecellars.co.uk - sells wine. He only delivers in the UK. You get free shipping if your order is over £250. Otherwise it's a flat rate of £8 for your wine to be delivered. He wants to add a flat rate of £22 for Saturday delivery, so the customer can choose between £8 next day or £22 Saturday deliver on checkout.

I have been all through the forum looking for a solution. I have even cloned flat.php to get 2 types of flat rate in the admin panel, but can't get the choice to appear in the front end.

All I want to do is offer 2 flat rates. I don't want it to be based on Zones, weight, units or price - just simply offer 2 types of rate for delivery to choose from.

Can anybody help me please?

2 flat rates for shipping - next day or saturday - how do i do this please?