Congratulations on your admit.
Not an expert on European programs. Just sharing some general advice, so user discretion is advised.
In the given scenario you can take the following few steps:
1) Write to IE and request for payment date extension.
2) Write to ESSEC to request for an expedited decision and maybe use your IE admit as leverage(not sure about the second part as don't know how useful it can be as it may depend on ranking of the programs.)
3) In the meantime realistically assess your chances at getting admitted at ESSEC and then maybe determine how feasible it would be for you to wait an year to apply to ESSEC again next year in the worst case scenario where you do not take up the offer from IE and dont end up with an admit from ESSEC(worst case scenario which I sincerely hope you dont have to face).