House price decreases quickly

<p>Bought a house through Nedbank in 2009 for R543000 but was Valued at R660000. in 2014 did a revaluation just to found out it drop to R600000,so in 2016 August I renovated my place which costed me R150000 to date and had all required documents from An approved building plan to Certificate of Compliance and A passed plumbing report from the Building Inspector..... So got Nedbank to come and re-evaluate my property which I came back with a revaluation of R630000.. Got a second from Sa homeloans and theirs was R720000 so now I ask Nedbank to clarify why it dropped in value even after the renovation. TILL to date no answers but just getting sent from pillar to post...... </p>