Just on the primary issue. If the indemnity is to be given by you to someone else, then you or another solicitor can issue the indemnity letter. You sign it and hand it over. If, however, the indemnity is to be given by a solicitor ( i.e. he/she is offering some kind of personal assurance to be personally responsible for a possible debt arising) then (a) the original solicitor may feel that he cannot give that indemnity because the file is virtually completed and he has no comback against you i.e.no ready access to funds to back up that indemnity and (b) a new solicitor will not give that indemnity.
As a by the way, I am fascinated by some of the demands my clients make of me such as, for instance, asking me to give financial undertakings ( i.e. personal promises/warranties/guarantees) without providing me with any comfort. Undertakings and indemnities should not and cannot be lightly given.
mf