Utility Warehouse Debt Collection Letter

Soph_elizabeth

Hi,
When I moved into my house the previous owner was with Utility Warehouse, meaning they automatically took over my energy supply before I switched to EDF.
I initially received an extremely high bill from them which I queried and it turned out that they hadn't correctly recorded my switch date so had over charged me.
I paid the correct part of the bill and was told the error would be rectified on the next months bill.
I received another bill a month later, and if I'm honest... forgot all about it and never paid! I'm so used to paying all my bills by DD it completely slipped my mind. I remembered this morning and have now paid it off, 3 and a bit weeks after I received it.
By pure coincidence i received a letter from a debt collection agency about an hour after I paid the bill threatening legal action over the outstanding amount. The debt collection letter came less that a month after the original bill and I received no reminders or warnings.
Soo my question is
- Can they send a debt collection letter less than a month after the original bill?
and
- Can they send such a threatening letter without so much as a 2nd or final warning?
Obviously I've paid the bill so nothing with go any further, I just worry that if I was elderly or vulnerable then this letter could be very upsetting.

Thanks