Business/domestic issue - plus paid bill twice!

Becarefulnotclever

Two questions in one here for anyone who may be able to advise me in advance of my contacting the water company - I would be most grateful!
Firstly, my property is residential and has been forever and a day - but I'm paying a business supplier - originally Affinity for Business which has now been taken over by Castle Water. I've known that for a while and not done anything about it but should I? Is it cheaper to be a domestic customer or should I just let sleeping dogs lie? Another part of this question - my property has two buildings and the second is let to a tenant - does that make it a business (as I am a landlord) or still all residential? Thank you. 

Secondly, I had a water bill from Affinity for Business for around £108 which I paid in March. AFB was then taken over by Castle Water and I received a letter from Castle Water on 20th April which was a 'Notice of Late payment interest and charges' saying because I hadn't paid they had instructed a Debt Collection agency to take over the issue. I panicked, thinking I'd forgotten to pay it, and paid again. I've just realised that now - the payments are both very clear on my bank statements. I'm assuming I'll just be refunded but has anyone got any experience with this at all? I'm also nervous that it had been put over to a Debt Collection Agency as I don't want my credit rating to be affected, especially given that I'd paid it on time!

Thank you in advance for your help.

Robin9

I am surprised that CW have involved Debt Collectors at this stage and for such a small amount.

Ring them on Monday and let us know the outcome ?
How did you get involved with AFB/CW ?

Becarefulnotclever

Hi there, thank you for responding. I have always paid the bill to Affinity for Business and kept meaning to let them know I wasn't a business customer but just never got around to it. Castle Water have taken over AFB from 1st April so I suspect something got lost in the transfer and they didn't realise that bill had been paid. I will call them tomorrow. No idea why they got a debt collector involved so quickly - all very odd!!!