Urgent Help required

Hi , I am from Kolkata....I have a query on very tipical issue..pls. help me.......One of my realtive have applied for PAN card in 2004 ...he had not got any PAN card till 6 months...after that he went to UTI (where he deposited the PAN application)...They written down a PAN card no on the acknowledgement slip. ...my relative start income tax filling on the basis of that PAN no....In the year 2010 he got the PAN card but in diferent No. .....Now as he already filled income tax return on the basis of old No. which have no proof ...what he would do....what is the official procedure to continue with the new PAN card no....Pls, help me...this is very urgent....