I am sick and tired of my dad's obsession about me calling Neptune Society to have him cremated today and I pretended that I called them.

Well, your Dad is obviously suffering from dementia & is exhibiting signs of agitation by insisting he wants to be cremated every day, while he's still alive. Does he do this as the evening approaches, suggesting maybe Sundowners Syndrome? Or does he make these statements all day long? If he's doing this in the evenings, Google "Sundowners Syndrome" to get tips on how to soothe his agitation and redirect him. If he does this all day long, call his doctor to let him know of this situation so he can maybe prescribe some medication to relieve his anxiety/agitation. It's not good for EITHER of you for him to be going on like this!!

Best of luck!

I don't understand. Why would you not just DO THIS for your Father. In fact have them pay a visit and give the options. Pre-paid cremation is at times cheaper than doing it at the time of death. Your Dad could express his final wishes for where his ashes are spread. I don't understand your reluctance.
Is there something we are missing?

OK, I had to take a break and look up the Neptune thing.. sound like a cremation service? Do you not want him to be cremated? It is OK to prepay for services like this. No different than prepaying for your funeral. If he just wants to prepay this it may make his mind easier in thinking its one thing you wont have to worry about. We had my dad cremated, and he passed suddenly so we just went with the local service that did that. It went so well mom wants me to use the same place, and I know her desires on her urn and service. My very Catholic Aunt was also so impressed by how well it went for dad that she went home and set up her cremation.. one less thing her kids have to deal with.