Speaking to councillors is always the best way forward, but you need to go further and get on first name terms with senior council officers, heads of departments, journalists and MPs etc. They find it much harder to say no to Alex, rather than to the world at large.
Also start a community group for the park. One of our first acts when we were served notice to quit our previous lake was to create "Friends of Eirias Park" who do litter picks, find grants for park improvements and soon your group is doing more for the park than the council ever did and the publicity attracts people who join to help.
Then you are an effective pressure group and not just some old blokes nagging for special treatment. Under pressure council got us a £45,000 grant to restore a bigger lake in the park.