Can a company change the method of severance payout if it was agreed to of a condition of a merger?

The publicly traded telecommunications company that I currently work for was merged (purchased by) another company nearly a year ago. As part of the conditions of approval of the deal by the FCC and/or the SEC the new company agreed to keep several programs in place for one year after the merger. This included the current severance package.

The new company's severance package is identical except for the method of payout. The old company package was a lump sum at time of separation and the new company is bi-weekly payments processed through payroll until the total amount of severance is paid out.

As I understand it, in California regardless of how the severance is paid out I will still be eligible for unemployment and the severance payments will have no impact on that. However that is not the issue at hand.

The last day to get a severance under a lump sum distribution (old company) is May 17 2017. Instead of ending (eliminating) my current position and paying out the severance in a lump sum, the company has pushed the date of separation to May 22th 2017 which we assume is because they don't want to pay out the lump sum as they are trying to save cash.

The question would be is this in violation of the terms of sale, keeping in mind that I believe this agreement was part of the approval process, most likely by the FCC? Certainly since I and others are intending to move out of the area, myself to Canada, this places an enormous financial burden on me not having the lump sum vs having to take bi weekly disbursements. I personally think that this is a underhanded move, again purposely pushing out the end date to insure that we cannot get the severance under the current policy, I am not sure though if I and others similarly affected would have a case. If we did, would this be something a qualified attorney would take on contingency? I have no idea what the payout would be if such a case was won, it may just be a fine against the company plus attorneys costs and maybe some sort of payout for the plaintiffs?

Since this is a time critical matter, I appreciate a prompt response. I am worried that I will be forced to take the severance four days past the cutoff date for the lump sum and of course anticipate that the contract will state that I cannot sue them once I have taken the package.

Also, since I have been a long time employee of the company and thanks to a generous payout I am looking a pretty decent amount of money for the payout and again, really would prefer the lump sum payout. Thanks!