Which reaction can I use to transform 2-hydroxyethyl-triethylammonium bromide to 2-hydroxyethyl-triethylammonium chloride?

We have synthesized 2-hydroxyethyl-triethylammonium bromide, then using it we have tried to prepare other salts. First we have used an ion exchange column to obtain 2-hydroxyethyl-triethylammonium chloride, after several tries we didn't get any good results. Following this example : [emim][Br] + KOH -> [emim][OH] + KBr [emim][OH] + CH3COOH -> [emim][CH3COO] + H2O We have tried to prepare 2-hydroxyethyl-triethylammonium acetate but for some reasons, the reaction didn't take place. Can anyone help me to find an alternative method to synthesize those salts using 2-hydroxyethyl-triethylammonium bromide.

What reactions did you use to synthesize the bromide salt?  Rather than converting the bromide salt to a chloride salt what about changing the sythesis to going directly to the chloride?  Are you sure you obtained the bromide salt and characterized it etc to make sure you got that product?