Sometimes plans run afoul of a high-income earner issue. The higher income earners at the company can't contribute more than the lower income earners. There's a nice fancy formula behind it, but maybe if you are one of the higher income earners, that's the reason?
Honestly it sounds like something else, though. Having run a 403b at a non profit, it took over a year to make a "simple" change to the plan. It involved having the retirement committee review and approve, then the CEO, then the plan lawyers review and approve, and finally the Board to approve. Then the plan document had to be amended and filed and etc etc. It was not a simple "change a number in a database" action. There are a lot of laws and regulations that govern retirement plans...