Dunno how damaged your bath is, stove, but we have one that had a huge ring of something corrosive thrown round it, leaving a big hightide sort of mark and big dirty looking drip runs all around it. Three years we've been here, and nothing seemed to want to scrub this "hightide mark" off the bath, until last week we decided to have a laugh putting some bicarbonate of soda mixed with vinegar on it.
Would you believe it, but the staining has mostly disappeared. Left the mixture on for a while, mebbe 30 mins, and then scrubbed off. Bingo. Bath about 85% "restored". Sorry to sound like an old wife (!), but it worked a treat. Maybe that might help?