singned contract and then loan was disapproved

i app**** for a loan with them. loan for r8000 was approved. i signed a contract telling me al the ins and outs. they told me that they must just do a work confirmation. suddenly they told me loan was off as my worknumber doesnt show on system. they gave me a number which wasnt my work number, i gave them the correct worknumber which they never phoned to confirm. they said they needed a lettwr to confirm and i told them that i cant get that as my boss left for australie. they then declined loan. i emailed them and asked how can a loan be approved and me signing a contract and then suddenly its off. i have been waiting for an answer for a whole week now. my question, how do you approve a loan by signing a contract before you have completed all your tracing and confirmations?