Sustainable Software Engineering (SSE) is slowly becoming an industry need for reasons including reputation enhancement, improved profits and more efficient practices. However, SSE has many definitions, and this is a challenge for organisations trying to build a common and broadly agreed understanding of the term. Although much research effort has gone into identifying general SSE practices, there is a gap in understanding the sustainability needs of specific organisational contexts, such as financial services, which are highly data-driven, operate under strict regulatory requirements, and handle millions of transactions day to day. To address this gap, our research focuses on a financial services company (FinServCo) that invited us to investigate perceptions of sustainability in their IT function: how it could be put into practice, who is responsible for it, and what the challenges are. We conducted an exploratory qualitative case study using interviews and a focus group with six higher management employees and 16 software engineers comprising various experience levels from junior developers to team leaders. Our study found a clear divergence in how sustainability is perceived between organisational levels. Higher management emphasised technical and economic sustainability, focusing on cloud migration and business continuity through data availability. In contrast, developers highlighted human-centric concerns such as workload management and stress reduction. Scepticism toward organisational initiatives was also evident, with some developers viewing them as a PR strategy. Many participants expressed a preference for a dedicated sustainability team, drawing analogies to internal structures for security governance. The disconnect between organisational goals and individual developer needs highlights the importance of context-sensitive, co-designed interventions.