You cannot change your Insolvency Practitioner but they can sell your case to another company if they wish.
It can be done and often is. A lot of companies are transferring/selling cases to other companies. A few companies are on a big case purchasing spree at the moment. It is becoming ever more frequent as IP’s retire, leave the industry or change the emphasis of their work stream.
But do not be bullied into accepting any new fees or changes to your terms and conditions when your practitioner changes.
You should not be effected in any way, other than to have a different point of contact, in fact it may be beneficial as a lot of small IVA specialists are selling their portfolio to larger organisations who have more resources and expertise.