Missed payment on credit file for house i vacated years ago

tentickles666

I'm hoping someone has some advice for me!
I just checked my credit file and theres a missed payment with Severn Trent for last month, its for a property I lived in with an ex years ago and I assume he is still there. I dont even recall my name being on the water bill when I was there, as I paid the rent and he paid bills, so I believe he has added it on maliciously. It was unfortunately an abusive relationship so no chance I'd unblock him and ask! 
I can show ST my credit file which shows i moved from the address to the new one, ive also sent them a screen shot to show my up to date account at the property I moved to. Will this be enough? I asked on WhatsApp and got a response saying I'd need to submit a final council tax bill but there wasn't one as far as I recall as the ex still lives there, so my name would have just been removed!
Thanks in advance