Sometimes it feels like a bit of a fight to the bottom when it comes to SIM only deals, with the likes of iD Mobile, Plusnet and Giffgaff all trying to undercut each other on price.

And now relative newcomer Smarty has just come up with a new deal that really raises - or should that be 'lowers' - the bar.It's delivering a two pronged attack in its January Sale.

Firstly, Smarty is introducing its cheapest tariff yet.

So instead of having to sign up to a 2GB data plan, you can now go for 1GB instead.

You still get unlimited calls and texts, but the £6.25 bills will look more attractive to anybody who isn't too bothered about using their smartphone away from the Wi-Fi.That's a great start, but the second new offer is really worth getting excited about.

Sign up to Smarty before February 4 and it will give you two months absolutely FREE! All you need to do is pay for your first month, and the next two will be on the house.

So if you're just looking for a stop gap - or simply really know a top bargain when you see one - then this should appeal.

If you only stay with Smarty for three months (you can quit anytime) you'll end up paying an effective £2.09 per month on its 1GB plan.

Extraordinary!Smarty's SIM only deals in full:Or check out all of today's best SIM only deals in the UKCredit back for unused dataOn the merits of the above promotion alone, Smarty is looking like a clever SIMO option at the moment for new and old SIM-free mobiles alike.

But its other USP is really worth reminding you about, too.It will give you money back for any data allowance that you don't use in a month.

So if you have a month where you hardly use your phone away from the Wi-Fi at all, you may be eligible for a partial refund. The tariffs include a base price of £5 per month which is non-refundable - then you'll get £1.25 back into your bank account for every 1GB of data you don't use.

So whichever plan you go for (other than the basic 1GB option, of course) if you use no data you'll only pay £5 per month and you'll still get unlimited calls and texts to play with.Worried about reception Again there's nothing to be afraid of - Smarty piggybacks on the Three network which covers 97% of the UK.