Just received my Schengen Visa - BLS SPAIN

I had my appointment on 10th June and received my passport today 8th July. Visa approved with multiple entries, 45 days valid till 4th October. Now I have another trip planned for 3rd October - 7th October, I had attached the tickets with my application. Now is there anything I can do to extend my visa for 3 more days? Or do I need to apply again? What are my options here? I just feel it is so weird to not get the visa covering my next trip and so expensive to apply for another visa.

Also can I apply for friends and family visa for Netherlands during my valid Schengen Visa?