I was receiving the maximum discount on my Council Tax bill due to my ow income. Then my circumstances changed, marginally for the better, so I immediately wrote to the relevant council department, with exact dates and figures quoted in my letter.
My next Council Tax bill still showed the maximum discount though, so I assumed that my income remained below the threshold for me to have to pay the full amount.
However att the very end of the tax year, the council sent me a demand for a full year's Council Tax, which had to be paid as a lump sum (i.e. with no option to make monthly payments).
I contacted my local councillor, stating that I felt that I'd been treated unfairly, as getting such a large bill out of the blue meant that I'd have to use a very expensive credit card to make the payment. She contacted the Head of Finance at the local council, resulting in my entire bill for a year's Council Tax being entirely written off (and thus saving me over a thousand quid).
So, rather than going via the Small Claims Process, I strongly suggest that, in the first instance at least, you should contact your local councillor. You're far more likely to get a swift resolution to your problem than by going through the courts - and it won't cost you anything either!