Hey guys so recently my car started using more petrol (like a tenner a day) and I haven't changed my driving style like how many miles I do or how fast I drive etc etc but my exhaust did start blowing and making a rumbly noise so I assumed that was why so I booked it in at a garage and he said it was the flexi pipe, so I payed him £65 to change it and the exhaust is much much quieter but it's still using petrol and it's still rumbling , now I need it fixing asap as I'm spending way too much on petrol and don't have enough for anything else , my question is any ideas what it could be and also where is the best place to go get it looked at, I live in walsall England and would be willing to travel abit but not ridiculously far ? 

The use of petrol suggests to me it's something more than the exhaust. Any garage will look at it for you but getting one that will be able to fix it for a decent price and do a good job is another matter. I'd suggest asking around friends, neighbours, colleagues etc. A local garage would be best, there should be plenty in Walsall.

Have you scanned for codes? Could be something as simple as a bad sensor.