HI - Just downgraded cars from a rather smart Alfa to a KA

lol.
Anyway just phoned up my insurers to see about changing insurance details and they want to charge me £20 admin fee ( which is fair enough) and then continue to charge me EXACTLY the same price as i was paying on the alfa !!!
Just so you know - Alfa is worth £3000, ins group 13, 1.8 engine with leather etc and the new KA is worth £1000, insurance grp 2 , 1.3 engine and boggo standard. - if i do a search for insurance on the Ka the company i use only show a premium of £150 a year where as the alfa is £220 a year - so i fail to see how the premiums can be the same.
So something amiss there imo.
Alternativly i can cancel my insurance and go with the post office for £80 a year lol - only problem there is that my current insurers will then charge me £45.59 which is a cancelation fee and the interest on the direct debit payments we agreed to.
Does the cancellation fee sound right ? Is that lawfull etc ?
Is there anyway i can cancel without paying the fee bearing in mind i have paid 6 months worth of £19 a month direct debits and only have 4 more left to pay.
In a nut shell can anyone offer any advice on what rights i have and what the insurance company can and cannot charge .
thanks