drinking oil?

My car is guzzling oil- at first I suspected a leak but that has been ruled out from my garage, they suspect it is burning the oil.
There is no dark smoke coming from the exhaust, im using about 1 2litre bottle a month which is around 1000 miles.

Someone mentioned some things to me-

1. piston rings and 2. thicker oil

Can piston rings be replaced and whats a rough price on this?
and also does using a thicker oil improve the comsumption so that is it not loosing oil. or could it ruin my engine further.

thanks, hope youi can help