arrogant non-paying tenants

[decca]

Please help! I live in scotland so all feedback must apply to scots law. Rented property on ast in june. June, july rent paid fine. Augusts was late, shortly after gas boiler broke down meaning no heating. Immediiately supplied heaters and phoned out normal gas engineer (corgi registered) who we always use. He agreed to fix outside his working hours so keeping cost down but ordered wrong bit twice then disappeared (this lasted a fortnight). Phoned other gas company who took a fortnight to fix it. Tenant was very arrogant from the start about this. Refused to pay septembers rent till heating was fixed which she said was the law i said it wasn't but let it slip. Once fixed she asked about discount off septembers rent which i agreed at £100 off. She said no she would only pay half. I said this was not acceptable and gave her to the following day to decide what to do. I gave her a few daysand when i phoned her she said she had contacted a solicitor and was wanted a copy of the first engineers certificate as she didn't think i had got it fixed quickly enough. She also stated a few other rights she thought she had which were all wrong making me realise she hadn,t contacted a solicitor but everything i said on the phone about sorting it out she replied with she would have to speak to a solicitor eventually saying i was being aggressive with her because i threatned her with eviction if she didnt pay rent then hung up. I am now faced with a £700 bill for boiler and no rent coming in to pay for it. What do i do to get rent quickly and efficiently.

p.s she pays rent cash and doesnt have a copy of tenancy agreement. Tenancy agreement was only signed by myself and tenant although 2 witnesses were there

update: oct. rent due today from tenant. spoke to her this morning and she says she is not paying rent til she speaks to lawyer on wed. i know she is stalling for time. rent must be paid. Can someone please give me advise.