Whom to use?
Stay far far (mind you Mexico is far enough!) away from Rishworth!
On that matter of Agent selection include also Sigma, Brookfield, VOR Holdings & GPS as TO BE AVOIDED!
Asiana and several Chinese Airlines both have very high failure rates.
Ask your new potential Agent and see what they reply.
Failures starting with security Clearances, License Checks, the medical, ATPL exam, ICAO 4 exam (if required) and the initial sim check and subsequent line checks.
Failures rates from 75-90% in some cases after almost a year into the Agreement are not unheard of.
Read the fine print in your Agreement, remember E-mails are not legally binding, ask a lot of questions from your Agent on areas that are unclear.
DO NOT SIGN ANY FORM OF A DOCUMENT in advance unless you are 100% satisfied with terms and conditions being offered and it is clear.
Limit the Agents period of representation to 3-6 months maximum during the evaluation phase until you are officially clear of all obstacles. Why - they could be sitting on their asses all the while you are thinking they are plugging away on your behalf. This way when the clock is ticking, they are also liable.
Even after being so careful myself, I am still owed sums of $ from many listed above and collecting from Mexico in Hong Kong, the UK, China or New Zealand is like trying from the South Pole!
Even though you are in a very tough spot, diligence and being very careful will at least get you some satisfaction in knowing the Agent you eventually sign up with, will at least ACT AS AN AGENT!