Looking for good monopod head

We often use monopods on zodiacs or other when photographing bears and such.....Recently had two high end "pro" monopod heads from Really Right Stuff fail when used on Safari in Africa...One had been used once before..the other was brand new....The clamp on one is held on by a single screw that came loose every 20 minutes...having to tighten became so often was interfering with shooting so one of us went to handholding...heads were easily designed to handle a Canon 5dIII with either a 100-400 or 200-400 but completely failed

Manufacturer has 5 year warranty but has refused to fixed the head that was bought for the trip and used one time...said the tightening damaged the unit....well what are you supposed to do when the fitting that holds your expensive gear is loose? Unsatisfactory response has been turned over to Visa to handle

Need solution quickly as we are headed to Spirit bears in a few weeks.

While my credit card company will deal with RRS for a full refund on a purchase made within the last 45 days, I looked at the RRS design....there are two small aluminum protrusions that are designed to keep the head from turning...If the one screw comes loose that holds the clamp in place, you are tightening against the small protrusions. No wonder the thing broke....after hand tightening with an allen wrench 3 times in an hours so we could focus on photographing and not equipment repair, the thing must have broken....terrible design and support of warranty and beyond all other things attitude.

Now on the good side, Robert Otoole sent me a note about Acratechs long lens product and I have ordered those as replacements. He has had them for years and they have been trouble free....Wished I had looked there first...I have one of their heads for seven years and love it....

Kirk enterprizes makes a very sturdy monopod head, it handles the heavy old Canon 600 IS and 1D body with ease.

Thanks Gerhard, I will look into it as I am replacing both failed RRS " pro" monopod heads..I have used Kirk's products before and they have been top shelf.....