New home construction

Hi, this is the first time I post here. About 6 months ago I began to build a house. The city required me to pay upfront for a sewer project they had completed costing me about $3,500 USD. (The city has a third party supplying water and drainage to the city) that third party installed sewers and the taps to hook up to them to all already built homes. My city paid an extra fee to have the empty lots get those taps installed on them also. The city had told me it would only take about 4 months for the sewers to be live and it would mean my house would not need a septic tank by the time I'm done building. Fast forward to today and the sewer project has been delayed and now the city is requiring for me to install a septic tank if I want to complete my house. I don't know what to do and I don't have money to spend on a septic tank. Can I ask the city for my money back? Can I sue the city? Nothing was given to me in writing as far as the date the sewers were to be completed but they did make me pay if I wanted to get a building permit. If anyone can help in giving me advise I appreciate it! Thank you!!