If it were me, I would get an old harden hose, fish it down the toilet at the dump station and rinse it out. I would then throw away the hose. This will work. You will get hosed (no pun intende) if you pay a service center to do this.
Steve Rinker
Rochester, NY
2013 Keystone Sydney 340FBH 5th Wheel, 12,280 lbs loaded (scale)
2015.5 GMC Sierra Denali 3500, SRW, Duramax, CC, Payload 3,700 (sticker- not scaled yet)
Take my posts for what they are, opinions based on my own experiences.