Option -A :
Follow below steps.
1. Remove stuck contact from Calculator Pro+.
2. In settings, enable "Force remove conversation"
1. Configure that number in Calculator Pro+ again.
2. Receive incoming MMS from that contact.
You should able to receive messages from that contacting in Calculator Pro+.

Option -B:
1. Install above application from market.
(https://play.google.com/store/apps/details?id=cn.com.opda.android.clearmaster&hl=en)
2. Open "1-Click Clear" application and go to "Comm. clear"
3. Select stuck conversation and try to remove.