Is the usage of "service" as a verb a recent phenomenon?

I am finding that people use the word "serviced" in place of other verbs such as served, repaired, helped, etc. Has the use of the word service always been acceptable as a verb? Or is that a more recent phenomenon?

No, the use of service as a verb is not particularly recent. The OED’s earliest citation in support of the meaning ‘to be of service to; to serve; to provide with a service’ is this in a book by Robert Louis Stevenson in 1893:

If I am to service ye the way that you propose, I'll lose my lifelihood.

Service as a verb is not uncommon. For example,

These appliances are serviced regularly.

ODO says of the verb service

The early sense of the verb (mid 19th century) was 'be of service to, provide with a service'

It depends what you mean by "recent". There are plenty of examples starting from the 1920's of "to service" in the sense of to perform a [regular] maintenance procedure on something "mechanical" (often, a car). It doesn't seem to have been used that way often, if at all, any earlier.

Back in the 1800s, "to service" was sometimes used to mean "to serve" in various senses (serve in a military capacity, to be of use, to provide with a service, to attend to someone's needs, etc.), but I think the modern usage is probably better described as verbification from the newly-emerging sense of maintenance of mechanisms. I'm sure there are earlier instances, but here, for example is a link to the Report of the Proceedings of the Annual Convention of the American Railway Master Mechanics' Association (1899) where I note that one reference to engine-service is hyphenated, but two others not - which strongly suggests that specific usage was "new and unusual" at the time.

I do not recognise OP's served and helped as synonyms of serviced in any modern context.