tank over flowing

[samual]

On closer inspection of our overflowing tank, we've discovered its the cold tank over flowing. The hot water isn't mixing into it like I thought before. We have tried adjusting the ballcock but this hasnt corrected the problem. Is it normal for water to dribble out from the valve on which the ballcock arm is positioned?
Also why if we turn the hot water tap on does this stop the overflow happening?
Need some ideas before I get a plumber in who might try to rip me off.
Thanks

 

[Bahco]

Renew the ball valve, could be some limescale inside causing it not to shut off properly.
Don't cost much and can be done yourself .
Ask your local plumbers merchant for guidance

 

[the plumber]

its sad that so many people think they are going to get ripped off. As a plumber i hear a lot of this but most of the people i work for normally recomend me surely there must be someone toy know has had work done or just phone a few plumbers and get quotes

 

[samual]

I'm sure you're a great plumber and there are alot of good plumbers out there. No offence taken I hope.
Thanks for the advice BAHCO, will try this.