I DIDN'T KNOW A MEDICAL CHECKUP COSTS $45

After a exhausting day that includes Math,Chemistry and GP lectures, I went to a clinic at GP to get a medical checkup which is required for me to attend OBS. I told the cashier that I need checkup and pass her my Medical Benefit card.

Cashier: sorry, you can't use this card for OBS medical checkup. (-_-)
Me: okay then.How much does the checkup cost?
Cashier: Hold on,I ask the doctor.Please have a seat.

Cashier: It costs around $30.
(I had $28 in my wallet)
Me: Oh I see.Hmm...okay I go home first to take more $.I'll be back later.
Cashier: Would you like me to keep your form here at the moment?
Me:okay

At home, when I was about to go back to the clinic,my mum called.
Mama: Bob,how come the checkup is so expensive? D=
Me: It's around $30.
Mama: Your head!The doctor said $45!Don't go to that clinic;go to polyclinic is cheaper.
Me: Hah?

Forget it,I'll go to polyclinic another day. I continued with my revision.
Half an hour later, I realised that I had left the OBS form at the clinic.
I'm tired of walking.Fasting somemore.When I take back my form, the staffs there appeared to have glum faces.Did my mum scold them? She is daring to do so.

Tonight,my neighbourhood is filled with noise from 2 communities. There's a street opera as well as terawih prayers within close proximity.