acting up indefinitely

I'm with the company about 3 years and like it. However i was asked to be a manager without any extra raise in salary or training, just a rationalization thing as the business is growing but they don't want to hire yet. Thing is I know i won't be good at it nor would i even like it, and i have said so - they think i can manage fine as I'm oldest in the group with most experience (doing what i do, not in managing what we all do). nobody else wants the job - no extra money only responsibility. I love my job but they won't take no for an answer that no, I do not want this extra headache tacked onto my job.
So what can i do about it?

I would definitely ring [broken link removed] to see if they can give you any advice.

Do you have a trade union who could help?

Thanks for the link, no union, barely a HR manager.

There is a huge difference between being good at your current job and being a good manager of people. It is also very hard to move from being 'one of the lads' to the manager of those same lads. It's a pity that your employer isn't smart enough to recognise this. Is there any training or other support such as mentoring that would help you get comfortable with managing people? What does your employment contract say about what your current role entails?

It is probably down to a matter of direct negotiation with the employer. Look for some kind of compromise. Perhaps you could take on some of the admin work associated with line management if someone else were to look after the performance management side?

Contacting employment rights office is the only solution I find at this point of time.