Get new architect/engineer to do retention?

Hannaho

Hi! Kceire, or anyone else who can advisee on planning professionals. As per my other posts re my sister's engineer saying she was exempt from planning and now finding she isn't, has to apply for retention and also has to pay levies of e3400. My sister's solicitor wants her to continue with the original engineer who made the mistake - told her that a two storey side extension did not count when considering 40 sq metre rule, and told her that she could extend the original rear statute barred extension, which lost her the statute barred exemption, all incurring a levy of e3400. Should my sister go with a new planning consultant costing e3100 for just the application? After numerous letters between the original engineer who gave the wrong advice and my sister's solicitor, the original engineer has agreed to waive his fee for retention, because my sister has to pay e3400 in levies. However, my sister doesn't trust him and feels really that he's not competent and won't be diligent in the application. Her solicitor feels that the engineer has all the drawings and it is easier to start with him, and that he owes my sister something for all the extra expense and stress. Would welcome some opinions on this - 3400 is a lot for my sister plus 3100 for planning applicaiton.