Plans by communications giant Talk Talk to sponsor school crossing patrols have been criticised.
The GMB said moves by the company to sponsor lollipop patrols in Wandsworth, south London, showed how frontline council services were being affected by spending cuts.
The union will stage a protest next week outside a meeting of the council to demonstrate against the plan, and to highlight cuts to other services, including meals-on-wheels.
General secretary Paul Kenny said: "Ending lollipop staff and the meals-on-wheels service in Wandsworth mocks David Cameron's claim that cuts would not hit frontline services.
"Getting a short-term sponsor to support lollipop staff is no way to keep kids safe crossing the roads to school.
"A wealthy area like Wandsworth can afford the £200,000 for the lollipop staff instead of boasting of having the lowest council tax."
Neither Talk Talk or the council made a comment.