Informal Interview

Hi guys, just a quick one. A week ago, I went for an interview for an Accounts Assistant Job. I was not successful. However, according to the agency that sent me to the company, they got a very positive feedback about my interview performance. Unfortunately an internal candidate got the job at the end.
The agency have called me again today to say the same company has another position of credit controller and if I am interested the hiring manager is happy to have an informal chat with me tomorrow. I am not happy about the salary as it's below the average credit control. (£18K) I would like to negotiate with him to see if he can move upwards if he really wants me. I have never negotiated salary before. Could you please assist as to how I should ask him?
The agency have called me again today to say the same company has another position of credit controller and if I am interested the hiring manager is happy to have an informal chat with me tomorrow. I am not happy about the salary as it's below the average credit control. (£18K) I would like to negotiate with him to see if he can move upwards if he really wants me. I have never negotiated salary before. Could you please assist as to how I should ask him?
Comments
I really appreciate your response but based on my experience, I feel this is too low. Your further comment would be appreciated.
Are you an accredited credit controller Lee with a recognised certification in that area? Personally, I think good credit controllers are worth their weight in gold and depending on the value of an organisations ledger, £20k a year for a £10m ledger with acknowledged problems is peanuts.
Sorry if this is a silly question, but what is an 'accredited credit controller?'
I have been doing credit control for 10 years and don't think I have come across that term!
Thanks
http://www.findcourses.co.uk/Credit_Control_and_Debt_Management_Level_3_107751.htm
http://www.icm.org.uk/default.asp?edit_id=563-28
Our old credit controller (who was also a full CIMA member) received (and we still get them long after he's gone) professional publications on credit control and risk management. Just like many other walks of life, there are regulating or certifying bodies even though they may be little known or of limited value.
My thoughts are if you can get a chance go for it jobs are hard to come by at the moment, if the wage is liveable its a job you can negotiate once your there and can see what you can bring to the company.
Jan