Bank blunder with security-urgent

Hello all, long time no see.
For all the legal eagles out there-I have an urgent question.
I am in the process of refinancing an old loan.
The security on all our loans, dating back the last 10 years, is based on a block of land, we bought in 1995.
4 years ago it was subdivided and cut in two. The old RP does not exist anymore, and has been replaced by 2 new ones.
There is still a mortgage outstanding on the block, but, for tax purposes we have been able to also half the morgage, and treat them as two seperate loans, claiming one and using the other as our PPR.
The bank security is based on the old RP, and is used for a lot of our properties.
I want to ensure that the spare block is not encumbered, and security free, and was going to sort this out with the bank.This was supposed to be the deal when we split the loan.

However, the way that they have it now, if anything ever happens to us, can they use the old RP as security even though it doesn't exist anymore, and therefore, in actual fact, are both the blocks unencumbered?

From a legal perspective, where does that leave the bank?

We had to have a valuation done, and the value of the one block is now the same as the two blocks combined, when they did the original valuation.
Upon reading the valuation, which I demanded from the bank, i also noted that the valuer has forgotten about 2500 sqm of ocean frontage common property. Subsequently our valuation should even be much higher, but I don't know if I should go and rock the boat, and get it all sorted. If I leave it,based on the incorrect valuation and based on the incorrect security, we are still fine, but is this in my best interest?