Guardianship 'Caution'. help please!

My mother has recently become incapable of looking after her financial affairs, so I, and my brother, have applied for, and been granted joint guardianship for her.

Now, we have been forced by the public guardian ( this is in scotland btw...) to gain a form of insurance called 'caution' that insures our mother estate against misappropriation by us, the guardians. Now I can understand the purpose of this in situations where a helper or non-related individual is applying for guardianship over someones finances. But in this occassion we are her only children, and are both heirs to her estate. So, in my view it seems obsurd that we need to spend over £1500 a year in insurance purely to prevent us misusing her estate ( infact when you think about it, we ARE misusing her estate by agreeing to PAY this form of extortion! ) ....

To add to this obsurd situation, there are only two insurance companies that provide this form of insurance. One of which rejected our application. So in fact we had no choice but to take the higher priced premiums of the second company. ( I read the transcript of the discussion in the scottish parliament when they were discussing the bill that introduced the requirement to gain caution, and they stated that the premiums would be only .5% or thereabouts, our premiums are more than double this).

Now that we have been granted guardianship, I feel that we aren't in a position to dispute the requirement of gaining caution. I feel that our solicitors were negligent in advising us during this process( a long story, I may keep for another time )....

So, in short, can you advice me on whether there is any case for us to dispute the requirement for caution based on the fact that we are the sole beneficiaries of the estate, and are therefore highly unlikely to abuse our position, as it would be us in the end that would lose out?

Do we have any legal standing in regards to the fact that we were not given a choice in insurance providers, and have therefore been subject to buying a product in a market that is in effect a monopoly ?

Any advice , discussions or thoughts on this subject greately appreciated!

Thanks all...
Pm