[Resolved]  HTC P3400i Phone — messages not sending

Address:

Andhra Pradesh

i have p3400i phone ... i am facing lot of problem with it... i am not able to send more than two messages... for every 2 messages network is refreshing and taking time for it.. an error message called the message could not be sent because the sim is not valid is shown on the screen.. but i tried changing different sims but the same problems are repeated but all those sims work in other mobiles.. i even got my mother board replaced for this set but prolem still continuing..... service center officers are not responding and saying to complaint to head office... i even not receiving calls but the calling persons can hear the network ringing but no message or alter is shown in the set.. so i am loosing important calls... plz gelp me soon before i complain in cosumer forum... my contact numbers [protected]...[protected]... plz let me inform the solution on these numbers