We understand that since you are an American Express Platinum card holder, part of the benefit is a complimentary upgrade to Le Club Accorhotels platinum card.
However, Le Club Accorhotels card status is valid for 365 days as per terms and conditions of the program.

If your cumulated activity still meets the criteria for your current status level, you get to keep the status, or be upgraded if appropriate, for a 12 month period.
Otherwise, your status is adapted to the level that corresponds to your overall activity, in compliance with the status level definitions. In all cases, a new card will be sent to you with the status based on the recalculated amount.

If you carry points over from one year to the next, status level assignment is nonetheless based on the number of hotel nights or points acquired over a consecutive period of 365 days.

As of February 28, 2015 that is, one year after your previous status level assignment, you had not reached the required conditions to obtain the next highest level. The total count of hotel nights and points is refreshed for each new period, which is why you are being informed at this time that you still need to acquire 12928 points or 54 nights to reach Le Club Accorhotels Platinum status.

We sincerely thank you for your loyalty.

We remain at your disposal for further information you may need.