Im travelling to China with single entry business visa valid for 3 months.

Anu, since you hold single-entry M type, if you exit PRC to HK or Macau, you need to re-apply for a new business M type to re-enter mainland PRC.
I don’t think you can change your single-entry type to a multiple-entry permit, or you can try to re-apply for a business M type with multiple entries, but it may be difficult.