Do you have any information on how your clients weren't able to reset their password? 

https://accounts.intuit.com/index.html 
Signing into the account here should get them logged in. Selecting "Try something else" will give users the option to recover their account. 

They must sign in with the email address associated with the Link. Once their logged in, they either need to change their Intuit Account email address to match the one you have or you'll have to uninvite the email you have for them and reinvite them with the email address they're using for their Intuit account.