English Drano....Yikes!

Since we moved in to our little humble abode here in London, our bathtub has had somewhat of a drainage problem. As you shower the water collects until the gravity pulls it down the drain all at once...about 15 min or so into the shower. Originally, we thought it was that the pipes weren't ventilated properly, but lately it's been getting a bit worse. I've been looking for a drano type product but have had no luck in our little corner of London. Last night, we were headed to Notting Hill to meet some friends for dinner and we went into a hardware store up there and asked for help. The owner pointed us to a product with pretty rudimentary packaging that said it was professional grade. We were psyched! After dinner we got home and Mike started reading the directions. This drain cleaner was sulphuric acid! It told us to pour a half pint down the drain. We did this once, twice, and on the third time, I think the acid was eating through the plastic cup Mike was using to pour as he felt the burn on his hand. This was some serious stuff! After the third dose, we had to ventilate the house as it was starting to smell a bit like sulphur. So the big question, did it work? Well, not really! It must just be the old pipes in this place! LOL! All of that for really nothing!