As per general and present policy exam centre change is not permitted by IGNOU.
Special case
In special case, Regional Centre gets authority to amend/ modify hall tickets before start of exam.
This authority is given by IGNOU headquarters for a limited period of time.
During this window/ time period, student can approach his/ her Regional Centre with the request to change exam centre.
But do remember, you should have very strong valid reason to change your exam centre.
If Regional centre concerned staff is not satisfied by your reason, the exam centre will not be changed. At present there is no fees for change of exam centre.