I'd absolutely get a new agent on the case. There's a house near me that's been on for ages, I've tried to ring the estate agent and they were absolutely hopeless on the phone, this bolshy-sounding teenager (work experience?) told me they couldn't book a viewing because their computer was broke and hung up.
I would view it if I could, but it's a bit out of my way and I'm not going to bend over backwards to chase it up when there are other houses on the market that are easier to view/buy and I think how awful would that EA be to deal with if I bought that house?
Also as a general rule, no viewings = very bad photos (or nowhere near enough) and possibly missing floorplan (or an inaccurate one that makes no sense e.g. windows, doors or walls missing).
Even at a giveaway price a lot of people won't waste time booking a viewing for the property if they can't see what it is particularly well, and then people get suspicious of things that are underpriced, too.
Big issues that put me off viewing:
a) Photos showing power lines, motorway or train tracks in the shot
b) Photos making it look like the kitchen or bathroom are unviable (no kitchen/bathroom usually means it's unmortgagable)
c) Photos making it look dirty or dingy
d) Photos making it look like the house has severe structural issues, mould, roof problems/leakage or plants growing through parts of the building etc
Obviously there are a lot more things you can do photography-wise to get more viewings/interest, but these are the main ones that make me roll my eyes and scroll on.
Also, have you updated the house during your ownership of it, e.g. new windows, new boiler, rewiring, new kitchen/bathroom, removed any ancient conservatory or shed that otherwise look costly to remove? If you've had it for 18 years and done nothing to it, it probably won't have increased much beyond inflation.
Lastly, have you gone on Rightmove and checked it's definitely on there? That's where most people look for properties these days and any EA who doesn't use Rightmove is not fit for purpose in 2023.