Postal Department — postal department gave wrong information

Address:

712708

Sir in early days all letter came to my address, now a very important letter which send by speed post by eden realty solaris returned to them due to wrong pincode 712708 which stated by esplanade post office, which statement is incorrect. Please do necessary steps.
My address which mentioned " soumya bhandari c/o late ajit kumar bhandari village and post garalgacha, district hooghly, garalgacha radhaballav pad, police station chanditala, near surobala vidyamondir, pin 712708.
Tracking number given by them ew[protected]in
Sir previous days and now also all letter which i collect in same address by speed post and what happened now for that pin code is not found i don't understand the issue.
I do given complain to postal department docket nos. Vide [protected] and [protected] and today replied by them the pin code of garalgacha had been changed from 712708 to 712311, but sir i want to inform you that 712311 is the pin code of dankuni post office, i also inform you yesterday already a letter delivered to my pin code 712708 via speed post from lic city branch
So i request you to please take necessary steps and expect a feedback from you